Laser cladding Ti-Ni/TiN/TiW + TiS/WS2 self-lubricating wear resistant composite coating on Ti-6Al-4V alloy

TiN reinforced Ni matrix composite coating with in-situ synthesized TiS lubricant phase were fabricated on Ti-6Al-4V alloy by laser cladding with NiCrBSi, TiN and WS2 powder mixtures. The phase compositions, microstructure, microhardness and tribological behaviors are investigated by X-ray diffractometer (XRD), scanning electron microscope (SEM) with energy dispersive spectrometer (EDS) as well as a multi-functional Tribometer. Effect of WS2 contents on the microstructure, microhardness and tribological properties were studied. And the corresponding wear mechanism was discussed. Results indicate that the hardness of the coating (about 900HV(0.2)) is significantly improved compared with substrate (370HV(0.2)). Coefficients of friction and wear rates of these coatings have been significantly reduced. Besides, laser-clad coating using the mixed powders of 50%Ni-30%TiN-20%WS2 has good anti-wearing and friction reducing effects, and the main wear mechanisms of that are abrasive wear and micro-plowing.